The proposed work will continue our studies on developmental genetics of cellular slime molds. These studies will include isolation of new drug resistant mutations and the genetic mapping of these and developmental mutations by parasexual means. Studies will also be continued on the role of the cell cycle in development. These studies will make use of a temperature sensitive mutation which specifically inhibits growth in the G2 stage of the cell cycle. Work will also be initiated on the characterization of surface polysaccarides in Dictyostelium. These studies will be concerned with the role of these molecules in the control of development and it is hoped to tie this in to our genetic studies. BIBLIOGRAPHIC REFERENCE: Katz, E. R. and V. Kao. Evidence for Mitotic Recombination in the Cellular Slime Mold Dictyostelium discoideum Proc. Nat. Acad. Sci. USA 71: 4025. 1974.